"I literally had the feeling that I was everywhere in the universe simultaneously." - excerpt from Mark Horton's NDE

Can't argue with that. When the brain is starved of oxygen, and starts dying from front to back, the last thing people experience is visions of bright, calming light. Happens to test pilots and others, too.

But a feeling is different from a fact. For instance, if these people had in fact been floating above themselves, they would have noticed signage and lights placed for their benefit.